Electromagnetic power device



sept. 22, 1925. 1,554,254

E. ZBINDEN ELECTROMAGNETIC POWER DEVICE Filed Dec. 14. 1925 Patented Sept. 22, 1925,.

UNITED STATES PATENT OFFICE.

EMILE ZBINDEN, or BERNE, SWITZERLAND.

ELECTROMAGNETIC POVTER DEVICE.

Application led December 14, 1923. Serial No. 680,778.

specification.

The present invention has reference to iinprovements in electromagnetic tools and relates more specifically to thatl class of electromagnetic power devices in which by the cooperation of continuous and alternating current coils a spring' influenced armature is made to reciprocate in synchronism with the alternating current, and the particular object of this invention is to improve the action of the armature-influencing springs by choosing them of different character so that by reason of their individually different natural vibrations or frequency they serve to compensate the irregularities in the operation of the spring` system as a whole and also the irregularities in the frequencyJ of the actuating.;- current, which irregularities in the prior art have been found to seriously interfere with the proper operation of the ndevice and often are the cause of fracture of one or more springs.

Cvlindrically coiled springs, which are caused to vibrate in axial direction, do not vibrate evenly throughout. Therejvill be set up nodal points where no oscillations will dccur and between suoli nodes bulges or loops will develop, very apt to cause in time fracture owing to local excess stresses. Furthermore,y such partial oscillations will injuriously affect the proper operation of the armature, inasmuch as in the known devices of this character the armature and spring; system or unit does not vibrate on a pure sine line, but on a deformed wave line caused by wave superimposition.

The use of a single spring; or several identical springs in this connection, thus, is conducive not only to fracture of the springs but also to uneven operation of the armature by reason of the stated partial oscillations.

ln order to do away with these serious drawbacks I employ for the indicated purposes a plurality of springs, each 0f which differs in natural vibration from every other spring of the system, with the result that combinedthey compensate to a large degree the individual vibrations, and a mean natural periodicity of the spring,` system is 0btained which overcomes or paralyzes the l0- cal excess stresses and thereby obviates or at least greatly reduces the danger of fractures and assures the perfectly timed and evenly powered operation of the armature.

'I he natural `frequency of the armaturespring suspension system is to be so chosen that it falls below the frequency of the altern nating,` current, whereby important advantages are obtained. properly the tool must have the character of an electromotor showingthe same amplitudes on idle running; or under load, that is to say, the armature must show a con- In order to operate stant deflection, and one of considerably less extent than if the frequencies were identical. The constancy of the deflections, however, aside from the weight of the armature and of the force and formation of the pole pieces, is dependent upon the choice of the spring suspension. If the natural frequency of the springs-armature system is equal to the frequency of the alternating current, then a considerable deflection of the arman ture is obtained, but the uniform sine oscillation of the system would seriously be affected by the tool operation. On the other hand, the tool operation would not proceed in a normal manner, since the best effect is obtained only when the armature oscillations develop on a pure sine line, tliatis to say at a constant amplitude.

If the natural frequency of the system is chosen to be higher than the current frequency, it is true, the armature can also be vibrated but in this instance with but little force, and it can readily be seen that a constant deflection with and without load cannot be obtained.

If, however, according to my invention, the natural frequency of the armature and spring` suspension system is chosen to be below the frequency of the alternating current, then the armature will show the tendency to lag,- within the phase relative to the current. latter, remaining in step therewith, as it were, with the effect that even strokes of constant force result.

The device, thus, already on running idle is loaded to some extent owing to this ent-rainment of the armature. During operation vibrations are set up which practically develop on a pure lsine line, because the It will then be entrained by the f springs ineach reciprocation otthe armature are iorced to 'do double duty, being first compressed and then extended aga-in, for contrary to the prior dev ices otrthis character, no special stop means are provided for limiting the reciprocations ol the armature. On starting, the armature immediately falls in step With the current and the amplitude o'lf. its oscillations` iapidly increases until it has reached its normal rate.

In order to malte my invention more readily understood, I will novivv describe it in connection With the accompanying drawing, in which Fig. l is a longitudinal sectionthroughI the new device on line L-l of Fig. 2, which latter is a cross-section on line II-II loit Fig. l. Fig. 3 illustrates schematically the electricalA connections.

The shell or case l, representing the stator, contains coils 3 which alternate with pole rshoes 2. The lcoils are ted from a continuous current source and are so inter" connected that each two adjacent magnet fields are oit opposite polar-ities. The axially reciprocating armature '8, suitably guided in the stator as at'll and l2, .is providedl with coils l5 connected to a source of alternating current, as at lo, and sointerconnected that the respectively adjacent magnet fields show opposite polarity. Annular pole members 13, supported on annular ribs lfl, partly cover-in the coils l5. The pole pitch, that isy the distance between the centers of each twoY pole pieces, o'tI the coils l5 is identical to that of the coils 3. The interspaees 17 -between the pole slices 2 are li'lled with nonmagnetic material and their width is substantially that ot the pole inemlaers 13. The co-operation oit the coils il and 15 is Well known in the art and need not be enlarged upon here.

Between the armature and the stator' there is interposed in'axial direction a plurality ot coiled springs 18, arranged in substantially cage-formation around the protruding armature extremity. These springs thus are easily accessible and are readily demountably secured at their ends to the stator and the armature respectively. The springs are preferably allot' `diitl'erent elasticity and serve, aside from their cliice ol normally keeping the armature in the position of rest in which the pole members 13 register with the interspace'sl', to attune the operative periodicity of vibration et the armature to the natural period of vibration or' the alternating current and also to practically eliminate self-vibration vin the individual springs.

' Special stop means` to limit the operative displacements of the armature are not needed, the spring suspension system by itself fully serving this purpose.

lllhat I claim is l. In a reciprocating electromagnetic power device of the character set forth, in combination, a stator, an armature axially reciprocable therein, and a plurality ol axially 'directed cylindrically coiled control springs of individually different natural irequency arranged substantially in cage formation about said armature and their' extremities respectively secured to said stator and said armature.

2. In a reciprocating electron'iagnetic power device of the character forth, op-

eralile by alternating and direct current, in

,coinbinatioln a stator, an axially reciprocable arn'iature in said stator, and means interposed between said stator andsaid armature for attuning the periodicity ot rrciprocation of said armature toV that ot the alternating current and tor eliminating seltvibration in these attuning means, coinprising a plurality off cylindrically coiled control springs ot individually different lrequencies and so chosen that the natural trequency of all ot these springs together with the armature is below that ot the alternating current.

EMILE lZBINlTEN. 

